Circuit breaker



June 7, 1949.

F. SHORT 2,472,233

CIRCUIT BREAKER Filed Nov. 17, 194s s sheets-sheet 1 F. SHORT CIRCUITBREAKER June 7, 1949.

3 Sheets-Sheet 2 Filed NOV. 17, -1943 INVENTOR. 'RHN/f SH01? 7".

Arron/vsn June 7, 1949. F. SHORT CIRCUIT BREAKER 3 Sheets-Sheet 3 FiledNOV. 17, 1943 HTTORNEK Patented June 7, 1949 CIRCUIT BREAKER FrankShort, Burke, Va., assignor of one-half to Louis V. Lucia, WestHartford, Co

Application November 17, 1943, vSerial No. 510,635 3 Claims. (Cl.20G-122) This invention relates to circuit breakers and moreparticularly to devices intended for automatically breaking an electriccircuit when sub'- Jected to an overload.

An object of this invention is to provide a circuit breaker having acurrent responsive element which is in series with an electric circuitcontrolled thereby.

A further object is to provide a circuit breaker wherein said element isselectively adjustable to automatically operate the circuit breaker inresponse to resistance of dilerent amperages in the circuit.

A still further object of the invention is to provide such a circuitbreaker having a current responsive element which is adapted to beconnected in series with an electric circuit controlled by said breakerand which is selectively adjustable to provide different resistances'inthe circuit for operating the breaker when under loads of dierentamperages.

A further object of the invention is to provide an automatic circuitbreaker having thermal responsive means acting as a conductor in theelectric circuit and operable t'o actuate said breaker when subjected topre-determined current loads.

A still further object is to provide such a circult breaker which can beinstalled in conventional types of Wall switch boxes.

Further objects of the invention will be more clearly understood fromthe following description and from the accompanying drawings in Which-Fig. 1 is a side view in central vertical section of a circuit breakerembodying my invention.

Fig. 2 is a. front plan view of the same removed from the wall box.

Fig. 3 is a front viewin vertical section on line 3-3 of Fig 1 with thelatch member and parts of the casing being shown in elevation.

Fig. 4 is a front view in elevation of the casing with some of thecurrent conducting parts mounted therein.

Fig. 5 is an elevational member.

Fig. 61s a front view in elevation of the operating member and adjustingmeans as connected in an electrical circuit; the said circuit beingindicated diagrammatically.

Fig. 7 is a view similar to Fig. 1 but showing plan view of the latchthe position of the switch when automatically moved to open position bythe current responsive operating member as indicated in dotted lines.

Fig. 8 is a similar view showing the switch when moved to open positionby the operation 0f the manually operable member.

Fig. 9 is a fragmental view, in central vertical section, showing amodied form of adjusting means.

As shown in the drawings, my improved circuit breaker comprises a casing5 of insulating material which may be mounted in any suitable mannerWithin a conventional Wall switch box such as indicated at'6. The saidcasing has mounted therein terminals 1 and 8 which extend through therear wall of the casing and have threaded openings therein to receivebinder screws for connecting thereto the ends of conductor Wires of anelectrical circuit. The terminal 'I is electrically connected with acontact member 9 and the terminal 8 is similarly connected to aconductor bar I0 which extends to a post II. Another contact member I2extends to a post I3,

A switch mechanism is provided which consists of a switch bar I4 that isadapted to bridge across and contact the contact members 9 and I2. Thesaid switch bar is carried on an inverted U-shaped rocker bar l5 ofinsulating material and which is pivotally' supported with its bottomextensions mounted in hook-shaped portions I6 and I1 in the spaced armsI8 and I9 of a cradle having side extensions 2|-2I with trunnions bywhich the said cradle is journaled in the casing 5 at the pivotal pointsindicated at 22-22.

The said cradle is provided with an oper-ating handle 23 which extendsthrough a cover plate 24.

A `spring anchoring bar 25 of insulating material is'carried at the endsof resilient supporting members 26l and 27 which are preferably made ofspring wire and'anchored respectively on the posts Il and I3. A switchoperating spring 28 is secured at one end thereof to a loop portion 29on the carrier I5 and at the other end to a, loop 30 on the saidanchoring bar 25.

A bi-metallic U-shaped operating member 3l is mounted on the posts Iland I3 and is disposed in back of the switch anchoring bar 25 for thepurpose to be hereinafter described. Also mounted on said posts, andelectrically connected aivaaee in parallel with 'said bi-metallicoperating member, I provide a resistance in the form of a helical coil32 having an adjusting screw-33 which is threaded thereto and has adisk-shaped head portion 34 whereby it may be rotated. The rim of saidportion 34 may be provided with an indicating line 35 which cooperates,as will be hereinafter described; with indicia on a scale 36 that iscarried on the post I3. Stop members 3'! and 38 may also be mounted onsaid posts Il and I3 for limiting the movement of the carrier I5.

A latch member 39, preferably also of insulating material and having adetent 43, is pivoted within recesses 4I4I in the casing 5. Spacedspring members 42-42 are secured to the said latch member, underlie thesame and engage the front plate 24 to retain the latch within saidrecesses and urge it towards its operating position with relation to theanchor bar 25.

The said latch member 39 is provided withan extension 43 which projectsthrough an opening 44A in the front plate 2li to serve as an indicator,

and it may also be used as a re-setting handle as will be hereinafterdescribed.

A latch operating member 45 is pivotally mounted at 46 to the handle 23and provides fingers which swing freely from said handle for operatingthe latch 39 as will be also hereinafter described.

When the above described circuit breaker is connected to an electricalcircuit, the bi-metallic operating member 3 I together with theresistance 32, are connected in series in said circuit and, asillustrated in Fig. 6 of the drawings, the said circuit includes theswitch I4, the contact members 9 and I2, a source of energy i1 andresistances 48--48 which represent'dierent appliances that may beconnected to said circuit.

The operation of my improved circuit breaker will now be described.

When the circuit breaker is in its closed position, as illustrated inFig. l, the electric current may flow from the terminal 'I to thecontact 3,'

through the switch bar Iii to the contact I2 and to the post I3, throughthe iJ-shaped bi-metallic member 3l and the resistance coil 32 to thepost I l, and through the conductor I3 to the binding post t. The saidbi-metallic member 3i and resistance 32 are connected in parallel andconstructed to carry current up to a certain predetermined amount ofamperage through the circuit. "Iherefore, should an overload above suchamperage occur in the circuit, the resistance in the said bi-metallicmember 3i will cause it to heat and warp in the direction of the springanchoring bar 25, as indicated in dotted lines in Fig. 7, and force thesaid anchoring bar outwardly until the anchoring point of thespring 28has been moved past the pivotal point of the switch carrier I in thehook portions Il. At this time, the said carrier will be rocked on itspivots and moved to the position shown in Fig. 7 wherein the switch bari4 is spaced from the contacts 9 and l2 and thereby breaking theelectrical circuit.

' As the switch mechanism is moved to the open position by the aboveoperation, the bar 25 will move past the detent 40 and the latch 39 willbe forced upwardly, by the springs'42-42`, moving said detent in thepath of the return movement of said bar. After the circuit has beenbroken, the bi-metallic member 3| will cool and return to its normalposition, leaving the said anchoring bar 25 in engagement with thedetent 40 against the tension of the spring members 26-21 It will benoted that the extension 43 on the latch 39 is now in its up position.This will indicate, from tion shown in Fig. 1.

the exterior of the plate 24, that the switchris open and that thecircuit has been broken due te the occurrence of an overload.

The above described circuit breaker may be re-set by simply moving thehandle 23 downwardly to the position illustrated in Fig. 8. The downwardmovement of the handle 23 will cause the fingers 45 to move the latch 39downwardly and disengage the detent 40 from the bar 25; thus allowingthe said bar to be returned, by the spring members 26-2'i, to its re-setposition which is also the normal on position of the circuit breaker.

After the circuit breaker has been re-set, the

switch mechanism may be moved to its closed or "on position by movingthe handle 23 to the posi- This will carry the hook portions I1-I I tothe position wherein the pivotal points of the carrier I5 are at theopposite side of the axis or center of the spring 28 and thus causingthe said spring to urge the carrier into switch closing position.

It will be noted that, while the anchoring bar 25 is in its normalposition, the circuit breaker r `y be operated to the on or offpositions in if. same manner as any ordinary switch. Howe when the saidanchor bar has been forced to ti. position illustrated in Fig. 7 by anoverload in the circuit, the switch cannot be closed until the lever 23is iirst moved downwardly to the re-set position and then upwardly tothe position shown in Fig. l.

My improved circuit breaker may also b'e re-set by simply forcing theextension 43 downwardly since this will disengage the bar 25 from thedetent 40, cause the said bar to move to its normal position and carrythe axis oi the spring 28 past the pivotal point of the carrier I5.This, however. will also cause the said spring 2B to swing the saidcarrier and iiove the switch bar I4 to the circuit closing or onposition.

It will be noted that the switch mechanism of my improved circuitbreaker cannot be moved to its circuit closing position until thecircuit breaker has rst been re-set by the downward movement of eitherthe lever 23 or the extension 43. This will assure an indication thatthe circuit has been broken through the automatic operation of thecircuit breaker on account of an overload in the circuit. Indication, ofthe automatic operation of the circuit breaker due to an overload, isalso provided, while the circuit is dead, when the operating handle 23is in its on position and also when the extension 43 is in its raisedposition, as' illustrated in Fig. 7.

Adjustability of the above described circuit breaker is obtained bymeans of the resistance coil 32 and the screw 33 which may be turned insaid coil until the indicating line 35 thereon is in register with theiigure on the scale 36 that corresponds to the amperage at which it isdesired to have the circuit breaker operate for automatically breakingthe electric circuit.

Assuming that the resistance of the bi-metallic member 3l is such thatit takes a current flow of three amperes before it will heat to atemperature which will cause it to operate the bar 25, it will bereadily understood that, when the screw 33 is positioned in the coil 32so that the indicating line 35 registers with 5 on the scale 36, theeffective length of the said coil will be such that it will have acurrent carrying capacity of two amperes; thus a total of live amperesiiowing through the circuit will cause the bi-metallic bar 3| to flexand operate tobreak the circuit as above described and illustrated inFig. 7. When the screw 33 is set so that the line 35 is in register withthe figure 30 on the scale 36, the coil 33 will have a lesser effectivelength which will decrease its resistance to the current so that it willhave a current carrying capacity of twenty-seven amperes and therebylraise to thirty amperes the amount of current required in the circuit inorder to heat the member 3| suiciently to cause it t0 operate. It ispointed out that since the coil 32 and the member 3| are connected inparallel, the amount of current fiowing through the bi-metallic member3| is in direct proportion to the resistance in the coil 32, which iscontrolled by the effective length thereof. Therefore, any change in theresistance of the coil 32 will also proportionately change the amount ofcurrent flowing through the member 3| and thereby render the said memberoperable under overloads of different 'intensities.

It will be understood, from the foregoing description, that I haveprovided simple and highly effective means whereby a circuit breaker,such as above described, may be selectively adjusted to operate underoverloads of diiferent pre-determined intensities. This is of particularadvantage since it provides for accurate and speedy calibration duringthe production of circuit breakers.

As shown in Figs. 7 and 8, means are provided for retaining the cradle2| in the on and oil positions. Such means may comprise a spring 49which is suitably mounted, such as on the cover 24, and is adapted toengage a boss 50 on the said cradle with an over-center action and exerta tension on said boss urging the cradle 2| to the opposite limits ofits movement.

My invention may also include adjusting means, such as shown in Fig. 9,wherein an adjusting screw 5 I, having a lock nut 52, is threaded to thebar 25 and engages the bi-metallic member 3|; thus providing acalibrating adjustment which, if desired, may be used in conjunctionwith or in lieu of the resistance adjustment which includes the coil 32.

My improved circuit breaker is highly desirable as a protection for theregular fuses in an electric circuit since it can be installed in thecircuit with said fuses and, by adjusting the circuit breaker so that itwill automatically operate at just below the amperage of the regularfuses, an overload in the circuit will cause it to be broken before thesaid fuses are blown and thus provide an opportunity to repair thedefect or remove the overload from the circuit before damage has beencaused to the regular fuses.

I claim:

1. A circuit breaker including a casing, electric contact membersmounted in said casing. a switch bar cooperating with said contactmembers, a carrier for said bar, a carriage pivotally supporting saidcarrier, a spring member connected at one end of said carrier and at theopposite end to an anchoring member movable to carry the axis of saidspring across the pivotal axis of said carrier, a current carryingmember responsive to an overload in said circuit for operating saidanchoring means to cause said spring member to move said switchmechanism to open circuit position, a latch member having a detent forengaging said anchoring means to retain said switch mechanism in openposition, means for manually operating said carriage to move the pivotalpoint of said carrier to the opposite side of said spring member, meansoperable with said carriage for moving said latch to release saidanchoring means, and means urging said anchoring means toward theirnormal position.

2. An electric circuit breaker including a casing, contact membersmounted in said casing, a switch bar cooperating with said contactmembers, a carrier for said switch bar pivotally supported at one endthereof within a movable seat, a spring member secured to said carrier,anchoring means'for said spring member, manually operable means formoving said seat to cause movement of said carrier by said spring intocircuit closing or breaking position, current carrying means in serieswith said switch and responsive to overloads in said circuit for movingsaid anchoring means to cause operation of said switch to open circuitposition, a detent for retaining said anchoring means against movementto normal position, and means on said manually operable member forcausing said detent to release said anchoring means and thereby re-setsaid switch.

3. An electric circuitbreaker of the character described comprising acasing having a front plate a switch mechanism mounted in said casing,said mechanism including a switch bar, a carrier for said bar, a springfor operating said carrier, anchoring means for said spring, means forplvotally supporting said carrier by one end thereof I Number andadapted to move the pivoted end across the axis of said spring to causeoperation of said carrier into circuit closing and opening positions,said anchoring means being movable from a normal position at one side ofthe pivotal point of said carrier to a position at the opposite sidethereof. a detent for preventing return of said anchoring means to saidnormal position, and an extension on said detent projecting through saidfront plate for indicating the condition of said breaker and operable torelease said anchoring means and position.

FRANK SHORT.

imiannENclazs crrEn The following references are of record in the fileof this patent:

UNITED STATES PATENTS Name Date 1,531,722 Adams Mar. 31, 1925 1,550,206Church Aug. 18, 1925 1,722,768 Schnetzler July 30, 1929 1,759,395Getchell May 20, 1930 1,793,954 Myers Feb. 24, 1931 1,872,122 Cook Aug.16, 1932 1,928,802 Wight Oct. 3, 1933 1,946,894 Brogger Feb. 13, 19341,966,051 Sperry et al. July 10, 1934 1,969,064 Field Aug. 7, 19342,092,327 Persons Sept. 7, 1937 2,123,063 Peters July 5, 1938 2,170,426Raney Aug. 22, 1939 2,283,736 Jackson Mar. 19, 1942 2,368,620 Runke-..1--.. Nov. 6, 1945 permit return thereof to normal

